Debris cutter for sprocket drive

ABSTRACT

In a track-driven tractor, stationary cutter blades are fixed to a chassis of the tractor and cooperating rotating cutter blades are fixed to a sprocket hub of the tractor. The cutting blades are operable to cut refuse entrained between the sprocket and the chassis, which tends to wrap around the associated hub, so as to avoid the build-up of refuse on the hub which otherwise can lead to unnecessary wear of the sprocket, the hub, and an assembly forming a seal between the hub and the chassis, as well as unnecessary fuel consumption.

BACKGROUND OF THE INVENTION

The present invention relates to improvements in land vehicles and, inparticular, to tractors used to disperse and/or compact refuse at alandfill.

PRIOR ART

The capacity of existing landfills has greatly diminished and the costof establishing new landfills has greatly escalated due to environmentalconcerns. Thus, it is important that refuse materials deposited in alandfill be distributed and compacted as fully as is practical. To thisend, track-driven tractors have been utilized to spread newly receivedrefuse. Currently, these tractors are fitted with sprocket drives thathave rotating hubs and sprockets attached to the hubs. The rotatingsprockets move the tracks which propel the tractor. A blade is providedon the tractor to distribute the refuse. A serious problem has existedwith the operation of this kind of equipment where refuse tends to betightly wrapped around the hubs as the sprocket drives rotate. Materialssuch as sheet metal, metal bar, pipe, rugs and other sinewy componentsare entrained by the sprocket and/or the track causing it to wrap aroundits associated hub. Typically, the entrained material accumulates aroundthe hub at the inboard side of the sprocket.

The accumulation of refuse on the sprocket drive has severaldisadvantages. A large drag resisting sprocket drive rotation isproduced causing unnecessary fuel consumption. The drive train issubjected to unnecessary wear to overcome this drag or resistance. Thesprockets and hubs wear out prematurely because the refuse accumulatedon the hub rubs against hub and sprocket surfaces causing severeabrasion. Additionally, the refuse accumulated on the hub rips upduo-cone seals provided to form a seal between the hub and the tractorchassis.

Complicating this situation is the lack of any quick, practical way ofremoving the accumulated material from its entanglement with a sprocketdrive. The practice is to remove the material with hand labor and thisis dangerous to the workman. There is a risk of grasping a razor sharpedge of a broken or torn article hidden in various unsanitary debris andeven heavy gloves may not afford sufficient protection to the workman'shands.

SUMMARY OF THE INVENTION

The invention provides a method and apparatus for eliminating thebuild-up of harmful accumulations of refuse material around the sprocketdrive of a track-driven tractor. The apparatus comprises a pair ofcutter blades associated with a sprocket drive. One of the cutter bladesis fixed on the sprocket drive for rotation with the sprocket drive andthe other is fixed with respect to the sprocket drive. Rotation of thesprocket drive causes its cutter blade to revolve in a path that sweepssufficiently close to the fixed cutter blade to produce a shearing orcutting action therewith. Material entrained by a sprocket and/or atrack that begins to be wrapped around a hub of the sprocket drive issevered by the pair of blades. The severing action prevents the materialfrom being wound in multiple ever-tightening turns. Once the material issevered, it tends to fall through an opening formed between the tractorand the track thereby avoiding a build-up of the same.

In the preferred embodiment, the cutter blades include cutting edgesthat are generally oblique with the sprocket drive axis and anglegenerally toward the opening formed between the tractor and the track.Additionally, the areas forming the blade edges are plate-like inconfiguration and can operate in either direction of rotation of thewheel. The disclosed cutter blades are arranged to be retrofitted onexisting tractors.

In one version of the invention, a stationary blade structure fixed withrespect to the sprocket drive comprises a cutting plate and a mountingplate oriented at right angles to one another. The mounting plate isattached to the chassis of the tractor by threaded fasteners. Therotating cutter blade structure is complementary to the geometric shapeof a hub of the sprocket drive and is welded to the hub. The cutterblade structures afford a highly effective trash cutting and sprocketdrive cleaning system with an extended service life.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a elevational view of a track-driven tractor employing thecutter blade assemblies of the present invention;

FIG. 2 is a fragmentary perspective view of the tractor of FIG. 1 in thearea of the sprocket hub assembly associated with the left side of thetractor as viewed looking generally toward the chassis;

FIG. 3 is a fragmentary perspective view similar to FIG. 2 but as viewedlooking generally away from the chassis;

FIG. 4 is a fragmentary elevational view of the sprocket hub assemblyassociated with the left side of the tractor taken along line 4--4 ofFIG. 1 with the track shown in dashed line for clarity; and

FIG. 5 is a perspective exploded view of the cutter blade assembliesillustrated in FIGS. 1-4.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The disclosures of U.S. Pat. Nos. 5,330,260, 5,451,100, and 5,553,932are expressly incorporated herein by reference in their entireties.

FIG. 1 illustrates an elevated sprocket tractor 10 of the type used bythe landfill industry to distribute refuge or debris. Commonly knownexamples of such tractors 10 are machines marketed by Caterpillar, Inc.under the model designations D8N, D9N, D10N, and D11N. The tractor 10includes a chassis 12 on which is carried an engine and drive traingenerally indicated at 14. The engine and drive train 14 selectivelypropel a pair of sprocket drive assemblies 16 for either forward orbackward rotation. One sprocket drive assembly 16 is located on the leftside of the tractor 10 and the other sprocket drive assembly 16 islocated on the right side of the tractor 10 (not shown in FIG. 1). Therotation of the sprocket drive assemblies 16 moves associated tracks 18comprised of a plurality of track shoes 20 to propel the tractor 10. Thesprocket drive assemblies 16 are located at an elevated position, thatis, higher than track rollers 22 located near the portion of the track18 engaging the ground. An adjustable blade is provided at the front ofthe tractor 10 to distribute the debris or refuse in the landfill as thetractor 10 moves back and forth over the landfill area being filled.

As best shown in FIGS. 2-4, each sprocket drive assembly 16 includes ahub 26 having a horizontal axis of rotation 28 and a sprocket 30. Thesprocket 30 has a plurality of radially extending teeth 32 for engagingand moving the associated track 18 as the sprocket 30 is rotated. Thehub 26 has a cylindrical outer portion 34, a frusto-conical centralportion 36, and a cylindrical inner portion 38. A mounting flange 40 islocated on the outer periphery of the hub 26 between the outer andcentral portions 34, 36. The mounting flange 40 has a series of axiallyextending and circumferentially spaced holes for receiving threadedfasteners 42 to mount the sprocket 30 to the hub 26. The inner portion38 of the hub 26 extends into the chassis 12 and is connected to theengine and drive train 14 for rotation of the sprocket drive assembly16.

A duo-cone seal 44 known in the industry has a plane of separation andrelative rotation at 46 which provides a seal between the rotating hub26 and the stationary chassis 12. The duo-cone seal 44 includescooperating hub and chassis sealing members 48, 50. The hub sealingmember 48 is annular-shaped and is secured to the rotating hub 46. Thehub sealing member 48 is preferably sealed to the hub 46 with an o-ring.The chassis sealing member 50 is annular shaped and secured to thechassis 12 adjacent the hub sealing member 48. The chassis sealingmember is preferably sealed to the chassis 12 with an o-ring. Therotating hub sealing member 48 cooperates with the stationary chassissealing member 50 to provide a seal at the plane of separation andrelative rotation 46.

In accordance with the invention, a pair of chassis or stationary cutterblade assemblies 54 are installed on the chassis 12 in fixed relation tothe associated sprocket drive assembly 16. Additionally, a pair of hubor rotating cutter blade assemblies 56 are installed on the sprocketdrive assembly 16 in rotational relation to the associated chassiscutter blade assemblies 54. Preferably, each of the sprocket driveassemblies 16 are constructed in essentially the same manner and arefitted with chassis cutter blade assemblies 54 and hub cutter bladeassemblies 56 that are essentially identical.

As best shown in FIG. 5, each chassis cutter blade assembly 54 is aweldment of heavy flat steel plate and includes a mounting plate 58, of,for example, 5/8 inch or 3/4 inch thickness and a cutting blade or plate60 of, for example, 11/2 inch thickness. The cutting plate 60 issubstantially perpendicular to the mounting plate 58 and is welded togenerally the center of the mounting plate 58. Alternatively, thecutting plate 60 could be welded directly to the chassis 12. Themounting plate 58 is sized and shaped for cooperating with at least aportion of the.outer face of a mounting flange 51 of the chassis 12.Preferably, the mounting plate 58 is a segment of a circular ring thatextends for approximately one-half the diameter of the mounting flange51 so that the two mounting plates 58 extend around the entire diameterof the outer face of the mounting flange 51. The mounting plate 58 has aseries of axially extending and circumferentially spaced holes 62 forreceiving fasteners 52 of the mounting flange 51.

The cutting plate 60 is sized and shaped for extending axially outwardfrom the chassis 12 and extends into a space or cavity formed betweenthe sprocket 30 and the chassis 12. The cutting plate 60 has a geometrywhich is complementary with the exposed surface of the chassis 12, theduo-cone seal 44, and the hub inner portion 38. The cutting plate 60includes a cutting edge 64 which is preferably at an angle to the axisof rotation 28 when installed. As best shown in FIG. 4, the cutting edge64 is preferably at an oblique angle which extends generally toward anopening 72 formed between the chassis 12 and the track 18.

As best shown in FIGS. 2 and 4, the chassis cutter blade assemblies 54are attached to the chassis 12 by the fasteners 52 of the mountingflange 51 on the chassis 12. The fasteners 52 extend through themounting plate 58 of the chassis cutter blade assembly 54 and into themounting flange 51. The cutting plates 60 of the chassis cutter bladeassemblies 54 are equally spaced about the outer periphery of the hub26, that is, located about 180 degrees apart. Preferably, one of thecutting plates 60 is located above the hub 26 and the other one of thecutting plates 60 is located below the hub 26.

As best shown in FIG. 5, each of the hub cutter blade assemblies 56 area heavy steel plate weldment of hot rolled steel and include a cutterblade or plate 66 of, for example 11/2 inch thickness and a pair ofgussets or straps 68 of, for example, 7/8 inch thickness. The straps 68are welded to opposite sides of the cutter plate 66 for bracing thecutter plate 66 against deflection out of its plane when installed. Thecutter plate 66 preferably has a mounting surface with a geometry thatis complementary to the exposed surface of the inner and centralportions 36, 38 of the hub 26. The cutter plate 66 includes a cuttingedge 70 that is complementary to the cutting edge 64 of the chassiscutter blade assembly 54. Therefore the cutting edge 70 is preferably atan angle to the axis of rotation 28 when installed and, as best shown inFIG. 4, the cutting edge 70 is preferably at an oblique angle whichextends generally toward an opening 72 formed between the chassis 12 andthe track 18.

As best shown in FIGS. 3 and 4, the hub cutter blade assemblies 56 arefixed to the sprocket hub assembly 16 by welding ends of the straps 68to the central portion 36 of the hub 26 and preferably welding theperiphery of the mounting surface of the cutter plate 66 to the innerand central portions 36, 38 of the hub 26. The hub cutter bladeassemblies 54 are equally spaced on the outer periphery of the hub 26,that is, located about 180 degrees apart.

As the sprocket drive assembly 16 turns, the cutting edges 70 of therotating cutter blade assemblies 56 sweep past the cutting edges 64 ofthe stationary cutter blade assemblies 54 in a circular path about theaxis of rotation 26 of the sprocket drive assembly 16. The various partsare proportioned so that there is a slight clearance of, for example,1/8 inch between the respective cutting edges 64, 70. When the rotatingcutter blade assemblies 56 pass the stationary cutter blade assemblies54, any refuse material entrained between the chassis 12 and thesprocket 30, and tending to be wrapped about the hub 26 of the sprocketdrive assembly 16, is cut or sheared by the respective cutting edges 64,70 or is at least scored by such cutting edges 64, 70 if not fullysevered. The cut or scored material is, consequently, unable to entwineitself around the sprocket drive assembly 16 and build-up in the cavityformed between the chassis 12 and the sprocket 30.

The rotating cutting edge 70 is substantially spaced from the sprocket30 and angled toward the opening 72 formed between the chassis 12 andthe track 18 so that the debris tends to fall through the opening 72 andprevents the accumulation or build-up of the debris within the cavityformed by the sprocket drive assembly 16, the chassis 12, and the track18. The rotating cutting edge 70 is preferably spaced from the sprocket30 a distance greater than ten times the operating clearance between thecutting edges 64, 70. Preferably, at least a portion of the cuttingedges 64, 70 are located radially outward from the plane of separation46 of the duo-cone seal.

The two stationary cutting edges 64 provide an efficient cuttingstructure because, upon each revolution of the sprocket hub assembly 16,refuse material can be double-cut, one time at each of the stationarycutting edges 64. Since refuse material is being carried up in oneinstance and being carried down in the other instance, there isassurance that such material, even if biased in some manner, will beadequately cut or scored by the cutting edges 64, 70. The two rotatingcutting edges 70, along with the two stationary cutting edges 64, cutthe refuse material four times upon each revolution of the sprocketdrive assembly 16. It is noted that other quantities of stationary androtating cutting edges 64, 70 can be utilized as long as there is atleast one stationary cutting edge 64 and at least one rotating cuttingedge 70. However, the illustrated configuration is believed to be themost efficient and effective. It is also noted that the cutter bladesassemblies 54, 56 are bi-directional and work efficiently in eitherdirection of sprocket hub assembly 16 rotation.

The disclosed cutter arrangement is particularly suited for retrofittingtractors 10 in the field. A kit of chassis and hub cutter bladeassemblies 54, 56 is provided generally as described above for aparticular model of tractor 10 and sprocket hub assembly 16 style. Ithas been found that a particularly efficient technique of fittingstationary and rotating cutter blade assemblies 54, 56 is to initiallyprovide the stationary cutter blade assemblies 54 with extra stock inthe cutting plate 60 at the cutting edge 64 so that there is someinterference between the stationary and rotating cutting plates orblades 60, 66. The hub 26 is manually rotated until the rotating cuttingplate 66 contacts the stationary cutting plate 60. Then, a cutting torchis used to burn the interfering material away from the stationarycutting plate 60 leaving a slight clearance of about 1/8 inch betweenthe resulting stationary cutting edge 64 and the rotating cutting edge70.

It should be evident that this disclosure is by way of example and thatvarious changes may be made by adding, modifying or eliminating detailswithout departing from the fair scope of the teaching contained in thisdisclosure. For example, the cutting blades can be forged or cast withintegral reinforcement gussets or mounting flanges. The invention can beapplied to other tractor drive sprocket arrangements such as theconventional arrangement where the drive sprocket is adjacent the groundat the rear of the track. The invention is therefore not limited toparticular details of this disclosure except to the extent that thefollowing claims are necessarily so limited.

What is claimed is:
 1. A track-driven tractor comprising:a chassis; atleast one track; at least one sprocket drive having a rotatable hub anda sprocket fixed to the hub for propelling said track; an engine and adrive train on the chassis for driving said sprocket drive for rotationof said hub about a substantially horizontal axis of rotation; arotating cutter blade mounted on said sprocket drive at a location whichrevolves in a path around said axis of rotation, said rotating cutterblade having a cutting edge in a zone bounded by said sprocket and saidchassis and being substantially spaced from said sprocket; and astationary cutter blade mounted to said chassis at a location generallytangent to the path of the revolving cutter blade, said stationarycutter blade having a cutting edge that cooperates with said rotatingcutter blade to shear refuse that tends to be entrained by said sprocketand wrapped around said hub, said cutting edge of said rotating cuttingblade being at an oblique angle to said axis of rotation of said hub. 2.A track-driven tractor comprising:a chassis; at least one track; atleast one sprocket drive having a rotatable hub and a sprocket fixed tothe hub for propelling said track; an engine and a drive train on thechassis for driving said sprocket drive for rotation of said hub about asubstantially horizontal axis of rotation; a rotating cutter blademounted on said sprocket drive at a location which revolves in a patharound said axis of rotation, said rotating cutter blade having acutting edge in a zone bounded by said sprocket and said chassis andbeing substantially spaced from said sprocket; a stationary cutter blademounted to said chassis at a location generally tangent to the path ofthe revolving cutter blade, said stationary cutter blade having acutting edge that cooperates with said rotating cutter blade to shearrefuse that tends to be entrained by said sprocket and wrapped aroundsaid hub; and an assembly forming a seal between said hub and saidchassis at a plane of separation and relative rotation, wherein at leasta portion of said cutting edge of said rotating cutter blade is locatedradially outward from the plane of separation.
 3. A track-driven tractorcomprising:a chassis; at least one track; at least one sprocket drivehaving a rotatable hub and a sprocket fixed to the hub for propellingsaid track; an engine and a drive train on the chassis for driving saidsprocket drive for rotation of said hub about a substantially horizontalaxis of rotation; a rotating cutter blade mounted on said sprocket driveat a location which revolves in a path around said axis of rotation,said rotating cutter blade having a cutting edge in a zone bounded bysaid sprocket and said chassis and being substantially spaced from saidsprocket; a stationary cutter blade mounted to said chassis at alocation generally tangent to the path of the revolving cutter blade,said stationary cutter blade having a cutting edge that cooperates withsaid rotating cutter blade to shear refuse that tends to be entrained bysaid sprocket and wrapped around said hub; and said cutting edge of saidrotating cutting blade being angled toward an opening formed betweensaid chassis and said track.
 4. A method of reducing the build-up oftrash around a sprocket drive of a track-driven tractor, said methodcomprising the steps of:(a) providing a movable cutting edge on thesprocket drive; (b) providing a fixed cutting edge at the sprocket drivethat cooperates with said movable cutting edge; (c) arranging said fixedand movable cutting edges so that said movable cutting edge issubstantially spaced from the sprocket and so that upon rotation of thesprocket drive, the movable cutting edge moves past the fixed cuttingedge in relative close proximity to it to sever material tending toaccumulate on the sprocket drive; and (d) arranging said fixed andmovable cutting edges to angle generally toward an opening formedbetween the track and the tractor such that the severed material tendsto fall out the opening.
 5. A method of reducing the build-up of trasharound a sprocket drive of a track-driven tractor, said methodcomprising the steps of:(a) providing a movable cutting edge on thesprocket drive; (b) providing a fixed cutting edge at the sprocket drivethat cooperates with said movable cutting edge; (c) arranging said fixedand movable cutting edges so that said movable cutting edge issubstantially spaced from the sprocket and so that upon rotation of thesprocket drive, the movable cutting edge moves past the fixed cuttingedge in relative close proximity to it to sever material tending toaccumulate on the sprocket drive; and (d) both said fixed and movablecutting edges being provided by flat plates and one of said plates beingcut for clearance after mounting and being brought into close proximityto the other plate by rotation of the sprocket drive.